Pump



Dec. 25, 195] r J B BRENNAN I 2,580,278

PUMP

Filed March 28, 1944 INVENTOR. JOSEPH B. BEEN/VAN A7 7 OBNEYS Patented fiec. 25, 1951 UNITED STATES PATENT OFFICE PUMP Joseph B. Brennan, Cleveland, Ohio Application March 28, 1944, Serial No. 528,372

9 Claims.

This invention relates as indicated to pumps and more particularly to an improved form of construction and method of manufacturing a pump which is designed primarily for the purpose of handling incompressible liquids and to deliver the same'at a constant rate with the amount of the delivery exactly the same for each degree of rotation of the pump.

This invention relates more particularly to the type of pump in which a rotor is mounted in a bore closer to one side than the other and provided with vanes extending through the bore and into engagement at their opposite terminal portions with the bore. i

It is among the objects of my invention to provide an improved method for the manufacture of pumps of this character.

It is still another object of this invention to provide a structure which is so formed as to minimize the amount of wear which ordinarily occurs in pumps of this character.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a longitudinal section through a pump embodying the principles of my invention;

Fig. 2 is a sectional view similar to Fig. 1 showing a modified form of-structure; and

Fig. 3 is a transverse sectional view of the structure illustrated in Fig. 1 taken on a plane substantially indicated by the line 3-3.

Referring now more specifically to the drawing and more especially to Figs. 1 and 3, the structure here illustrated comprises a body I having a boss 2 adapted to rotatably support a shaft 3 on which is mounted a rotor 4.

, 2 form of a hollow cylinder and provided with radial slots in which are slidably mounted a plurality of blades or vanes I I. The cylindrical opening 5, within which the insert 6 and the rotor 4 and the associated blades H are all mounted, is closed by means of a removable cap i 2 held in place by a plurality of bolts 13.

Excepting where otherwise specified throughout the following description, all complementary surfaces of the several parts of the assembly are ground to a close running fit. -Extremely close tolerances can be maintained because of the fact that pumps of 1 this character generally handle incompressible liquids which may them:elves be lubricants, or which may contain entrained lubricants.

The insert 5 is, as previously indicated, cylindrical on its external surface so as to closely en- The central portion of the body I is provided with a cylindrical aperture 5 adapted to closely embrace an insert 6. The details of the insert 6 will be explained in detail at a later point;

The central portion of the body I is provided with extensions 1 and 8 in which are formed the inlet and discharge openings 9 and I0 respectively.

The rotor 4, or more particularly that portion of the inner end of the shaftt. is generally in the gage the walls of the opening adapted to receive the same, and suitable means, not shown, such as dowels or other expedients, may be employed for the purpose of locking the insert 6 against rotation in the body I. The insert 6 on its inner periphery comprises two concentric segments of arcs I 4 and I5 of different radii, such arcs being joined by curves I6 which are similar but opposite. The arcs, curves, and vane lengths are so proportioned that the vanes at their opposite terminal portions are each in contact at all times with the inner periphery or bore of the insert 6. I 1

The preferred method of arriving at such relationship of parts as to maintain the condition just defined will be explained in detail at a later point in this description.

While the ends of the blades or more accurately their terminalportions have been illustrated in disclosure of my invention, all refinementssuch as the rockers or shoes on the ends of the blades, and other conventional expedients sometimes employed in pumps of this character, have been omitted. It is to be understood, however, that the principles of my invention may be employed in connection with any such previously known refinements whenever it is desired to utilize the advantages of any such refinements Irrespective of the manner in which the bore or inner surface of the insert 5 is formed, it is obvious that as the rotor rotates in a counterclockwise direction as viewed in Fig. l, the blade at the five oclock position in Fig. 1 will, during rotation of 90, be caused to slide radially in the rotor until it reaches the one oclock position. There are two forces which must be overcome in thus moving any, blade inwardly first, the inertia of the blade inself, and second, the centrifugal force incident to the movement of the rotor. Since pumps of this character usually operate at extremely high speeds, both of these forces are generally of considerable magnitude.

The are l 5 is substantially a portion of a circle,

so that a vane, in passing from the seven oclock position to the five oclock position, has, zero, radial acceleration. Immediately such blade passes from the five oclock position toward the three oclock position, its radial acceleration approaches a high value causing a considerable stress to be placed on the vane as well as the bore of the pump with which the'vane end is maintained in contact under considerable force due to inertia and centrifugal force as above explained.

It is one of the principal objects of my invention to provide in the assembly some means for minimizing the shock incident to each blade thus being subjected to extremely high radial acceleration. This can beaccomplished in a number of ways, as for example by increasing the flexibility of the blade by forming near its terminal portion a reduced cross-sectional area generally indicated at H in Fig. 1. When this relieved area is formed on the vane and extends radially inwardly for a substantial distance, it serves the dual function of not only providing a local decreased cross-sectional area in the vane, but at the same time relieves the bearing area between the trailing edge of the blade and the slot in the rotor. thus'increasingthe length of that portion of the vane which may be flexed under the influence of the forcespreviously referredto.

De ending upon the relative sizes of the rotor and blades, this ob ect of my invention may be accomplished by relieving only the wall of the slot along the trailingedge of the vane without actually relieving the vane itself. This will be.

found sufilcient for my purposes when the crosssection ofthe vane is sufficiently small so that enough flexure will take place intheincreased length of blade permitted to flex by virtue of the relief in the wall of the rotor slot." I

While accordingly this object cf'the invention may be accomplished by providing merely a.

clearance between the blade and rotor slot wall (either relieving the blade or therotor, or both), nevertheless, from a manufacturing procedure it will generally be found that this ob-,

ject can be attained most readily by merely providing an area of reduced cross-section in the blade, with such relieved area extending into the rotor slot for a substantial distance.

It should be noted that clearance between the blades or vanesv and the rotor. may befprovided on both the forward and rear side' of,the bla cles; v

thus producing a structure which may be operated in either direction of relative rotation ta, tween the rotor and stator.

It will be observed th'at'in the preferred em bodiment ofmy invention, the curves l4 and iii are concentric and that the 'rotor 4 is mountedconcentric with such curves." In the emb'odi ment illustrated in Fig. 1, the radius of the rotor is substantially less than the radius of the smaller of the two curves. This provides a substantial clearance between the rotor and stator throughout the entire periphery of the former. This is a definite advantage in reducing the rate of wear between the rotor and stator, especially when the material to be handled by the pump has, entrained solid particles ,or when it is not expedientfto entrain in, the stream of liquid handled by the pump an amount of lubricant sufiicient to provide adequate lubrication between the rotor and the curve M.

In the embodiment illustrated in Fig. 2, all of the parts are the same as those illustrated in Fig. 1, excepting that the radius of the rotor 4 is slightly greater, and in this case, is substan tially equal to the radius of the curve is. This type of structure is entirely satisfactory for use when the material handled by the pum contains no abrasive foreign material, and additionally includes. a sufiicient amount of lubricant, or, itself, acts as a lubricant for the close running fit between the rotor and stator.

As previously indicated, another important object of my invention is to provide a pump ofthe character described which will deliver exactly the same amount of incompressible liquid for each degree of rotation of the pump. 1 am aware that much effort has been expended in attempting to arrive at a solution of this problem. In all cases, however, the workers in. the prior art have attempted to solve this problem either by the use of a particularly selectednumber of vanes, or by the use of a carefully calculated mathematical curve for the curves It which join the arcuate portions of the bore. These prior art efforts have not beensuccessful in producing any pump which can truly be said to deliver an equal amount of incompressible liquid for each degree of rotation of the'pump. A structure 'may be made up as closely as possible to the theoretically perfect design. However, no means is known whereby it is possible to reproduce in metal on a commercial basis the mathematically perfect conditionsand specifications which 'the' prior art has laid down yielding astructure which has truly pulsatiom' less flow, i. e. a pump'which will deliver exactly the same amount of incompressible liquid for each degree of its rotation.

In accordance with myinvention, this can be accomplished by first constructing a model pump in-whichthe curves are reasonably accurate reproductions ofthedesired mathematical shapes. Thus; the two arcs are ground to as nearly practical concentricity and to the predetermined radii, andthe connecting curves are ground as nearly as possible to assume the desired shape which may be either a li'mac'on curve or a portion of an Archimedean spiral with the ends of such connecting curves as nearly as possible tangent to the'arcs which they connect. Into such stator is assembled a cylindrical rotor-of either of the forms of Figs. 1 or Z'and with blades'or vanes 'ofsuch length so as to as nearly as possible will preferably be in the neighborhood of the:

speed at which the pump is designed to operate.

om he discharge. sifleb fi' h ti e therelw betaken'off a connection to a' liquid column so positioned that it is not influenced by any external' vibrations, excepting vibrations which occur in the liquid column itself. By observing reflected light on the surface of such liquid column, one may accurately determine the presence or absence of any vibrations which if present will cause a distortion in the surface of the column.

The model pump thus assembled is run and it will always be found to have a pulsating discharge irrespective of how carefully the parts may have been made. By carefully observing the disturbances created on the surface of the liquid column, it is possible to determine the angular position of the vanes responsible for such disturbance, and the pump can then be disassembled and corrected to eliminate the pulsation thus determined.

After repeated trials, it will be found that all of the-irregularities will finally be eliminated and the surface of the liquid column remain truly quiescent denoting uniform delivery from the pump for each degree of its rotation.

An alternative procedure which may be followed in removing the pulsations from the model pump is to fit each of the vanes at its boreengaging end with an abrasive element which will automatically wear off more rapidly the minute irregularities in the bore of the pump, so that by merely running the model pump for a predetermined length of time it will be found that these abrasive members by such honing action have automatically modified the inner periphery of the bore so that a nulsationless delivery is secured. As soon as obser ance of the surface of the liouid column denotes that this condit on has been reached. the model pump is prom'otlv stopped, disassembled, and the lap ingin blades re laced with permanent blades of the pro er length.

The foregoing is a description of the manner in which one may prepare a model of a truly pulsationless pump. In general. after one such model has been built, it is possible to reproduce that model by using it as a guide or template in the quantity re roduction of other pumps like it. Such quantity re roductions may on occasion be found to contain slight imperfections asobserved in the liouid column test previously explained which may be removed if desired by a procedure s milar to that outlined for the production of the model itself. It will generally be found. however. that the reproductions can be brought into perfect condition much more quick- 1y t an was the original model.

While the ouantitv reproductions may be found to contain sli ht irregularities. the nature of such will generallv be so minute as to be tolerated since they will be of considerably lesser magnitude than those imperfections or irregularities found in the model as first constructed and any commercial'form of similar pump heretofore made.

It is believed that one reason why present commercial structures, even though most carefully prepared according to exact methematical formulae, still contain objectionable pulsations is because the stresses set up in the pump itself during use tend to change the individual elements or their proportional relationship sufficiently to give rise to pulsations in the delivery. In accordance with my improved method, however, all of the clearances which insure the delivery of the pum are finally determined under 6 the very conditions under which the pumpwill ultimately be called upon to operate. 1 All of the herein described improvements which comprise my invention may be applied to any of the prior art-forms of pumps generally similar to the form chosen herein for purposes of illustration. Examples of such prior art forms are illustrated and described in U. S. Patent No. 1,922,951 granted to Hawley on April 15, 1933, and No. 2,165,963 granted to Curtis on 'July 11, 1939. v

. This application is a continuation-in-part of my co-pending application, Serial No. 412,300, filed September 25, 1941, issued as Patent No. 2,344,964, March 28, 1944. Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

l 1. In a pump of the character described, the combination of a pump body having a bore, the normal cross-section of which is defined by two concentric arcs of unequal radii, with vane extending and retracting curves joining adjacent ends of said arcs, a rotor mounted concentrically with said arcs, vanes slidably carried by said rotor and in engagement at all times at their opposite terminal portions with the inner periphcry of said bore, the terminal portions being alternately exposed outside the rotor, said rotor and vanes provided with a tapering clearance effective throughout revolution between the rotor and each vane Where the latter emerges from the rotor and in extent longer than the maximum exposed portion of the vane and longer than the vane thickness.

2. In a pump of the character described, the combination of a pump body having a bore, the normal cross-section ofwhich is defined by two concentricarcs of unequal radii, with vane extending and retracting curves joining adjacent endsof said arcs, a, rotor mounted concentricallywith said arcs, vanes slidably carried by said rotor and in engagement at all times at their opposite terminal portions with the inner periphery of said bore, the terminal portions being alternately exposed outside the rotor, said rotor and vanes provided with a tapering clearance efiective throughout revolution between the rotor and the trailing edge of each vane and in extent longer than the maximum exposed portion of the vane and longer than the vane thickness.

3. In a pump of the character described, the combination of a pump body having a bore, the normal cross-section of which is defined by two concentric arcs of unequal radii, with'vane extending and retracting curves joining adjacent endsof said arcs, a substantially cylindrical rotor mounted concentrically with said arcs, vanes slidably carried by said rotor and in engagement at all times at their opposite terminal portions with the inner periphery of said bore, the terminal portions being alternately exposed outside the rotor, said rotor and vanes provided with a tapering clearance, efiective throughout revolution, between the rotor and each vane where the vanes project from the rotor and in extent longer than the maximum exposed portion of the vane and longer than the vane thickness, the radius of said rotor being less than the radius of the smaller of said concentric arcs whereby the rotor is free from contact with the arc surfaces.

amazes -tI; f ;:.3 f numnzof't-he; character d bed; th combination. of a pump, body having, a bore, the normal Qmss-section. of which is. defined by two Concentric arcs of unequal,:radii, with vane extending and retracting curves joining adjacent endsof said arcs, a substantially cylindrical rotor mounted concentrically with said arcs, vanes slid.- ablycarried by said rotor. and in engagement: at all times attheir opposite terminal portions with the inner periphery of said bore, the terminal pontions being alternately exposed outside the rotor, said rotor; and vanes provided with, a tapering clearance, effective throughout revolution, between the rotor and each vane where the latter emerges from the rotor and in. extent longer ma nline-maximum expos dv portion or: the vane andlonger than; the, vane; thickness, said" pump being characterized inthat the-radius; ofxsaid 16 .1 91? 'isysubstantially equal to: the radius. of" the smaller of saidconcentricarcs.

5. In; a pumpof the character described, the combination of a pump body having a borethe normal crossgsectionof which is; defined by two concentric arcsof unequal-radii, with vane extending and retracting curves joining adjacent ends of saidarcs, a rotor mounted concentrically with said arcs, vanes slidablycarriedby said rotor and in engagement at, all times attheir opposite terminal portions with the inner periphery'of said bore, the terminal portions-being a1ternately-ex-.. posed outside the rotor, the cross-sectionofeach of said vanes being relieved by an end taper ,longerthan the ,maximumpexposed portionof the vane and longer than the vane thickness;v

6. In a pump, of thecharacter described, the combination oi da pumpbody. having abore, the normal crossesection of which is defined by two concentric arcs of-unequal radii, with. vaneexe tending and retracting curves joininga-djacent ends oi saidarcs, a. rotor mounted. concentrically withsaid arcs, vanes slidably carried by-said rotor and in engagement at all timesnat theiropposite terminal portions with the inner periphcry of saidbore, the termina1 portions being alternately exposed, outside the rotor, the cross-section of each of saidvanesbeing relieved byia-n end taper longerthan; themaximum exposed portionof the vane and longer than the vane thickness to increase the fiexibilityof: the vane in the plane of its; movement.

7. In a; pump of; the character described, the combination Off a pump body' having a: bore, the: normal cross sectionof which is defined by two concentric" arcs of unequal. radii, with vane ex-; tending andrctracting curves joiningadjacent' ends of said; arcs,v a, rotor mountediconcentrically with said arcs, vanes slidably carried by said rotor and in engagement at all times-- at theiroppositeterminaliportionswith theinner periphcry of said; bore, the terminal portions. being alternately exposed outside: the. rotor, each of said vanes relieved in a local areaby an end taper longer thanthe maximum exposed portionof'thevane and longer than, the vane thickness, said pump. i being characterized in that theradius" of said rotor is substantiallyless than the: radius of the. smaller of said concentric arcs whereby the rotor is free from, contact with the arc surfaces.

.8. In; apump. of the. character described, the combination-of a; pumpbody having'a bore, the normal crossrsection of which is defined by two concentric arcs of unequal radii, withvane extending and retracting curves joining adjacent ends of saidxarcs, a: rotor mounted concentrically with: said arcs; vanes slidably' carried by said rotor-and in engagement atall times at their opposite terminal'portionswith the inner periphery ofrsaid bore, theterminalportions being alternately exposed outside the rotor, each of said vanesrelievedin a local area by an endtaper longer'than the maximum exposed portion of the vane and longer than the-vane thickness, said pump. being characterized in that the radius of. said rotoris'substantially equal to the radius of thesmallerof'said concentric arcs.

9.'In a pumppf the character described, the combination of a pump body having a bore, the normal cross-section of which consists substantially'oftwo concentric arcs of unequal radii, withrvane extending and retracting non-concen-' tric arcportions joining adjacent ends of said arcs, a substantially. cylindrical rotor mounted concentrically with said arcs, vanes slidably carried by said-rotor and'in'engagement at all times atftheir opposite terminaliportionswith the inner periphery of'said bore, the terminal portions being alternately EXFOSEdYOUtSidB the rotor and being relieved by a taper in extent longer than the maximumexposed portion of the vane, the nonconcentric arc portions of said bore being the product of-trial and error shaping.

' JOSEPH BJBRENNAN.

REFERENCES CITED;

The 'following references are of record in the file o'f'this patent:

UNITED STATES PATENTS Number" Name Date 1 ,649,256 Roessler Nov. 15, 1927' 1,748,744 Woolson"; Feb. 25, 1930 922,951 Hawley Apr. 15', 1933" 1,971,601 Dilg- Aug. 28, 1934 1,988,213: Ott Jan.'15, 1935 1,996,8'75- McCann -s Apr. 9, 1935' 2,015,124 Pfeiffer Sept. 24, 1935 2,126,200 Linderman Aug. 9, 1938 2,165,963: 'Gurtis July 11,1939 2,192,588 Heckert: Mar. 5,1940 2260,2388 Davis Oct. 28, 1941 2,302,411 Behrens Nov. 17,1942 2;344,964 Brennan Mar. 28, 1944 2,352,941. Curtis July4, 1944 'FQREIGN PATENTS Number Country Date 7,478 Germany 1878' 23.9.78. France Sept. 27, 1921 

